<p>It is shown that information is a natural and legitimate phenomenon, a property inherent in matter. The conditions for its emergence are formulated. The sources of information uncertainty in the processes of perception/understanding are analyzed. Based on the principle of complementarity, the uncertainty ratio for documentary information is introduced. The typology of types of information and its forms related to the phases of existence is given. It is shown that data, information, and knowledge have a fundamentally common nature and a common “effective” part, differing only within the framework of the functional role approach, determined by the corresponding context. Because information is an entity of the second order of complexity, which presupposes a non-atomic mode of existence, three groups of information properties are defined: fundamental, attributive, and pragmatic.</p>